Abstract: In this study, the role and the importance of the sense of smell were discussed and in the context of the sense of smell, the effects of lemon essential oil aroma on students’ attention level, cognitive learning and memory were studied. The study was carried out in English lessons on fifty eight 4th grade primary school students, 29 of which were in experimental group and 29 of which were in control group. The experiment lasted two months. During the experiment, lessons were performed in a classroom atmosphere given lemon aroma in experimental group, while lessons were performed in normal classroom atmosphere in control group. In the research, pre-post test method, independent samples t test and paired samples t test were used. Data gathered from the research, showed that the lemon essential oil aroma increases students’ attention level, enhances memory and relating to these it has positive effects on cognitive learning. These results showed that the sense of smell and aromatic stimulus, which had been neglected so far due to the effect of visuality, may have more crucial role on cognitive learning. Thereby, in order to ensure more effective cognitive learning, as a support and addition to visual and auditory stimulus in learning period, the role of aromatic stimulus is worth to be investigated.